There are a great many harsh environment applications in which cables carrying electrical and/or fiber-optical conductors are used to network submersible devices such as pumps, motors, and environmental sensors. In these applications, the cables are usually either terminated directly to the devices, or are terminated to connectors which then connect to the devices.
The term “cable termination” as used herein consists of the union between a cable's conductive elements and the respective conductive elements of a connector or other appliance to which the cable is attached. For convenience the part to which the cable is joined will hereinafter simply be called a “connector” with the understanding that it could be any sort of device. In harsh environments such as that found in sewers, ponds, or in seawater, for example, cable terminations are used to attach waterproof cables to submersible connectors.
The most widely used type of harsh-environment electrical cable termination consists of a cable-connector junction over-molded with a resilient material such as neoprene, polyurethane, or polyethylene. The over-mold renders the union impermeable to the exterior environment and protects it from mechanical damage. Over-molded terminations have the disadvantages that they must be made in a clean, controlled laboratory environment and require specialized chemicals, molds and other equipment. Under some conditions molded terminations also suffer from de-lamination of the bonds that bind and seal them to the other components. Representative examples of such terminations can be found in the open literature of major underwater connector manufacturers such as Seacon, Teledyne Impulse, Kemlon, and several others. Over-molded terminations generally represent old art.
A second sort of harsh environment electrical termination is completely mechanical, relying on layered elastomeric seals to protect the conductor junctions. Representative examples of this sort of termination are found in U.S. Pat. Nos. 7,182,617, and 7,690,936. This type of termination is field installable and repairable without specialized equipment; however, its use is restricted to very light-duty operations because there are no provisions to keep cable torque, bending, compression, or tension from working directly on the conductor junctions.
Another, more robust, type of harsh-environment cable termination houses the joined conductive elements of the cable and connector in a pressure-compensated chamber that is filled with a mobile substance. These terminations are installable and repairable in the field without the need of chemicals, molds or other specialized appliances. Pressure compensating the terminations relieves much of the stress on the conductor junctions, and reduces the possibility of environmental fluid intruding into the termination. Historically the mobile substance used in these terminations has been a dielectric grease, gel, or oil. More recently, lubricious powders have been proposed as the mobile substance, as in U.S. Pat. Nos. 9,116,323 and 8,899,841. For convenience in this document the mobile substance will simply be called fluid or oil, with the understanding that it could be any suitable material that remains mobile over the termination's entire operating ranges of lifetime, temperature and pressure. Typical examples of prior art fluid-filled terminations are disclosed in U.S. Pat. Nos. 3,877,775, 4,039,242, 4,673,231, 4,940,416, 6,796,821, 7,182,617, 7,429,193 and 7,614,894, and in foreign patent EP2252442. A cursory review of fluid-filled termination prior art reveals its ubiquitous complexity.
Components commonly used in oil-filled cable terminations include a flexible portion of the compensation chamber's wall that allows the chamber to adjust for volume and pressure changes. In terminations wherein the bitter ends of cables enter the oil-filled compensation chamber, breakout boot seals are often used to seal the interfaces where individual conductors issue from the cable's end. In addition to providing an isolative layer around otherwise exposed portions of electrical conductors, boot seals are intended to keep the chamber oil from escaping into the cable's interstices. Such oil loss can quickly lead to chamber collapse and catastrophic termination failure. As discussed in U.S. Pat. No. 6,796,821, prior art elastomeric breakout boot seals are easily displaced from their sealing positions, particularly in applications wherein there is rough handling or an overpressure of mobile material within the cable itself that might extrude into the boot seal and push it out of sealing engagement or even completely off of the cable's end.
There remains a need for a fluid-filled termination whose breakout boot seals remain in sealing position on the cable end to which they are installed, even in the case where there is an unseating overpressure within the cable itself.
The invention disclosed herein is a field-installable, removable, and repairable cable termination of the fluid-filled type. It integrates a breakout boot seal and a flexible-walled fluid chamber enclosure into a unified component, thereby yielding an assembly which is much simpler than prior art terminations. The assembly includes a pressure relief feature which vents any mobile material extruded from the cable's end into the outside environment, and not into the compensation oil chamber. It also includes two unique methods for managing optical fibers within the termination. The disclosed embodiments are for a simple unarmored marine cable-to-connector termination, but it will be obvious to those familiar with the art that it can equally well be adapted for more complex applications such as for armored cables. The invention should find use in a wide variety of applications wherein the high reliability of fluid-filled, field-installable and repairable terminations is required.